Lancing devices are used to penetrate the skin of a subject and obtain a sample of blood or other body fluid, as in the testing of blood sugar levels by diabetics. Typically, a lancet having a sharp point is translationally mounted within a housing portion of a lancing device. The lancet is driven by a spring or other biasing means to cause the sharp point to extend a small distance through an opening in the housing and into the subject's skin, creating a wound from which the sample of body fluid is collected. The housing optionally includes a pressure surface for “pumping” the wound to enhance sample size, and may also incorporate a capillary tube or other sample collection media. The endcap of the housing or a portion of the housing adjacent the lancet opening may include an open window or a transparent section for viewing the sample collection site, and may also include one or more sample size indicators for comparing the size of a sample to a desired sample size. Example lancing devices are shown in U.S. Pat. No. 5,356,420; U.S. Pat. No. 5,397,334; and U.S. Pat. No. 5,439,473, all of which are hereby incorporated herein by reference.
Lancing devices typically are intended either for a single use or for multiple uses. Single-use lancing devices generally are disposed of after one use. For example, in a hospital or clinic, it is desirable to provide a single-use lancing device that can be used on a patient and then disposed of to eliminate any risk of infection to subsequent patients or caregivers from exposure to residual body fluids remaining on the lancing device. Accordingly, single-use lancing devices oftentimes include a disabling mechanism to prevent accidental or intentional re-use of the device. Various forms of disabling mechanisms are available, and are well known in the art. For example, the disabling mechanism may comprise a return spring for retracting the sharp point of the lancet back into the housing after a single use, break-away elements or a frangible link in the cocking or triggering mechanism to prevent re-arming or re-firing the device after a single use, a locking element, and/or a shield for blocking travel of the lancet.
Because single-use lancing devices normally are disposed of after one use, they generally are relatively simple in construction so that they can be economically manufactured in large quantities. However, most known single-use lancing devices are too costly and/or are not true safety lancets. For example, many single-use lancing devices include a housing, a lancet having a body and a tip, a drive spring for propelling the lancet, an actuator for firing the drive spring, and a retraction spring and disabling mechanism to prevent reuse of the lancing device. With this number of parts, the cost of the lancing device is higher than most users desire. And some other single-use lancing devices eliminate the retraction spring and disabling mechanism to reduce cost. But then these lancing devices permit reuse, so they are not true safety lancets.
Accordingly, a need exists for lancing devices that are simple in construction and therefore low in cost. In addition, it would be desirable for such lancing devices to include disabling means so that they cannot be reused. It is to the provision of lancing devices meeting these and other needs that the present invention is primarily directed.